GB2273492A

GB2273492A - Tamper evident shrink sleeve

Info

Publication number: GB2273492A
Application number: GB9226592A
Authority: GB
Inventors: Andrew Mcclure
Original assignee: Smurfit Ltd
Current assignee: Smurfit Kappa UK Ltd
Priority date: 1992-12-21
Filing date: 1992-12-21
Publication date: 1994-06-22
Also published as: GB9226592D0

Abstract

A tamper-evident shrink sleeve has on its inside surface a tear tape 13 bearing a holographic image or pattern visible from outside the sleeve. The tear tape is perforated along its length to make it difficult to remove the sleeve without destroying the tape, the perforations penetrating both the tear tape and sleeve. The tear tape is preferably at least 5mm wide and is fixed to the inside of the sleeve by adhesive which is strong enough to prevent removal of the tape from the sleeve without damaging the tear tape. <IMAGE>

Description

TAMPER-EVIDENT SHRINK SLEEVE This invention relates to a tamper-evident shrink sleeve.

Tamper-evident shrink sleeves have long been used in the packaging industry to prevent products from anonymous interference or opening. The sleeve, which is usually transparent, is positioned over the opening of a container and shrunk to form a close-fitting seal. Thus the product cannot readily be tampered with without first removing the seal.

Conventionally, shrink sleeves incorporate so-called tear tapes, which locally reinforce the material of the sleeve and assist the removal of the sleeve. They provide strength for tearing off the sleeve in a single action by the user. Further, the conventional sleeve is normally provided with a line of perforations adjacent one or both sides of the tear tape, which constitutes a weakened tear line along which the sleeve will normally split when the tear tape is pulled, and thus provides for predictable removal of the sleeve.

An example of a conventional tamper-evident shrink sleeve as referred to above is described in more detail with reference to figure 1 of our co-pending British Patent Application No. 9221172.1 which gives details of typical materials used and methods of construction, and whose contents are incorporated herein by reference.

Usually, tamper-evident seals are indistinguishable from one another unless they are printed with the manufacturer's logo or other identification. However, printed seals can be copied.

It is therefore an object of the present invention to provide a tamper-evident shrink sleeve giving a greater degree of security than conventional sleeves.

Accordingly, the present invention provides a tamperevident shrink sleeve comprising a sheet of shrinkable material in the form of a sleeve, the sleeve having a tear tape bearing a holographic image or pattern visible from outside the sleeve, and the tear tape being perforated along its length.

The advantages of the invention are twofold. First, the provision of the holographic tear tape in itself provides extra security compared to conventional printed sleeves, since it is much more difficult to duplicate. Secondly, the provision of perforations along the tear tape itself, rather than adjacent the side(s) of the tear tape as in the case of conventional shrink sleeves, means that the holographic tear tape is itself likely to be split when the sleeve is removed.

Thus, the tape cannot be re-used by someone intending to re-package the product after doctoring it, for example.

Preferably, the perforations penetrate both the tear tape and the sheet material in common, and the tear tape is provided on the inside surface of the sleeve.

Also, the tear tape preferably has a width of at least approximately 5 mm, to enable the hologram to be seen clearly.

Embodiments of the invention will now be described, by way of example, with reference to the accompanying drawings, wherein: Figure 1 shows part of a tamper-evident shrink sleeve according to a first embodiment of the invention, and Figure 2 is a cross-sectional view of the shrink sleeve of figure 1.

It is to be understood that figures 1 and 2 show only part of a usually much longer sleeve which is cut to length as required for the particular article to be packaged.

Referring first to figures 1 and 2, the tamper-evident shrink sleeve there shown comprises a sheet 10 of shrinkable film in the form of a sleeve 11. Materials used for the sleeve are usually shrinkable by heat, the most common ones being PVC (poly vinyl chloride) and PET (poly ethylene teraphthalate) and including OPP (oriented poly propylene) and OPS (oriented poly styrene).

Although these materials can be extruded into sleeves, it is more common to form flat sheets into sleeves by bonding to form a seam, which allows for a tear tape to be attached to the inside of the sleeve or a scuff-resistant image to be printed. This is the case in figure 1, where a bonded seam 12 is shown extending along the sleeve.

The sheet material forming the sleeve is either bonded using a solvent, or ultrasonically. Since the sleeve is usually formed flat, an overlap 15 (figure 2) is usually left on the inside to prevent the opposite sides of the sleeve being stuck together. The seam 12 has to be strong enough to bear up to material shrinkage.

In accordance with the embodiment of the invention, prior to the sheet material 10 being made into a sleeve as described above, a holographic tear tape 13 is affixed to that surface of the sheet material 10 intended to be on the inside of the sleeve 11. Then, when the sheet material 10 is made into the sleeve 11, the tear tape 13 extends along the inside surface of the sleeve. This tear tape 13 bears, on its outward facing surface, that is to say the surface adjacent to the sheet material 10, a holographic image or pattern. The sleeve 11 is transparent, at least in the region of the tear tape 13, so that the holographic image or pattern is visible from outside the sleeve. The hologram may be a two dimensional or three dimensional hologram bearing, for example, the manufacturer's logo. Alternatively, it can be a random diffraction hologram.

Further according to this embodiment of the invention, a line of perforations 14 is provided along the length of the tear tape 13. This too is formed before the sheet 10 is made into the sleeve 11, but after the tear tape 13 is attached to the sheet material. Thus, the perforations 14 penetrate fully through both the tear tape 13 itself and the underlying sheet material 10.

The tear tape 13 should be at least 5mm wide to permit the hologram to be clearly visible, and depending on the size of the product on which the sleeve 11 is to be used, a tear tape 1Omm or more wide may be used. Holographic tear tapes suitable as the tear tape 13 are commercially available from, for example, Supastrip International of Nottingham, England and ELEF plc of Shepshed, Leicestershire, England, and are typically supplied on 30 micron polypropylene or PVC film.

The tear tape 13 may be stuck to the sheet material 10 using a water-based adhesive. Alternatively, it could be applied by glue or a solvent-based adhesive, applied using heat or ultrasonically. Of course, the adhesive should be clear, at least in the thickness used in the present application. Further, the glue or other adhesive should be strong enough to prevent removal of the tear tape from the sleeve, since although the sleeve will normally be removed by tearing along the perforations 14, removal by cutting elsewhere could be done and the adhesive should be strong enough to pull away the hologram pattern from the tear tape.

The tear tapes supplied by the above mentioned ELEF plc are self-adhesive.

The advantage of the above construction of shrink sleeve is that because the tear tape is itself perforated, it is destroyed when the seal is removed. It is therefore difficult to remove the tear tape in one piece, giving protection against duplication of the seal. By actually perforating the tear tape the perforation is reinforced, reducing the chance of tearing into the body of the sleeve and leaving the tear tape largely intact.

It is also possible to provide two or more lines of perforations along the tear tape 13 itself, either by performing two perforating operations or, where the tear tape 13 is wide enough, by folding the tear tape at an edge of the sleeve and perforating through the double thickness of tear tape.

Claims

CLAIMS:

1. A tamper-evident shrink sleeve comprising a sheet of shrinkable material in the form of a sleeve, the sleeve having a tear tape bearing a holographic image or pattern visible from outside the sleeve, and the tear tape being perforated along its length.

2. A tamper-evident shrink sleeve as claimed in claim 1, wherein the perforations penetrate both the tear tape and the sheet material in common.

3. A tamper-evident shrink sleeve as claimed in claim 2, wherein the tear tape is provided on the inside surface of the sleeve.

4. A tamper-evident shrink sleeve as claimed in any preceding claim, wherein the tear tape has a width of at least approximately 5 mm.

5. A tamper-evident shrink sleeve as claimed in any preceding claim, wherein the tear tape is fixed to the sleeve by means which damages or destroys the tear tape if the latter is pulled from the sleeve.

6. A tamper-evident shrink sleeve substantially as described herein with reference to figures 1 and 2 of the accompanying drawings.